Re: [PATCH v2 5/8] PCI/AER: Introduce ratelimit for error logs

[Karolina Stolarek <karolina.stolarek@oracle.com>]

On 14/02/2025 03:35, Jon Pan-Doh wrote:
> Spammy devices can flood kernel logs with AER errors and slow/stall
> execution. Add per-device ratelimits for AER errors (correctable and
> uncorrectable). Set the default rate to the default kernel ratelimit
> (10 per 5s).

I'd rephrase the last sentence to say "Add per-device ratelimits for AER 
correctable and uncorrectable errors that use the kernel defaults (10 
bursts per 5s)", but it's just a nit.

Overall, it looks good to me:

Reviewed-by: Karolina Stolarek <karolina.stolarek@oracle.com>

> 
> Tested using aer-inject[1]. Sent 11 AER errors. Observed 10 errors logged
> while AER stats (cat /sys/bus/pci/devices/<dev>/aer_dev_correctable) show
> true count of 11.
> 
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/gong.chen/aer-inject.git
> 
> Signed-off-by: Jon Pan-Doh <pandoh@google.com>
> ---
>   drivers/pci/pcie/aer.c | 24 ++++++++++++++++++++++++
>   1 file changed, 24 insertions(+)
> 
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index b4f902fd5ef6..c5b5381e2930 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -28,6 +28,7 @@
>   #include <linux/interrupt.h>
>   #include <linux/delay.h>
>   #include <linux/kfifo.h>
> +#include <linux/ratelimit.h>
>   #include <linux/slab.h>
>   #include <acpi/apei.h>
>   #include <acpi/ghes.h>
> @@ -88,6 +89,10 @@ struct aer_report {
>   	u64 rootport_total_cor_errs;
>   	u64 rootport_total_fatal_errs;
>   	u64 rootport_total_nonfatal_errs;
> +
> +	/* Ratelimits for errors */
> +	struct ratelimit_state cor_log_ratelimit;
> +	struct ratelimit_state uncor_log_ratelimit;
>   };
>   
>   #define AER_LOG_TLP_MASKS		(PCI_ERR_UNC_POISON_TLP|	\
> @@ -378,6 +383,10 @@ void pci_aer_init(struct pci_dev *dev)
>   		return;
>   
>   	dev->aer_report = kzalloc(sizeof(struct aer_report), GFP_KERNEL);
> +	ratelimit_state_init(&dev->aer_report->cor_log_ratelimit,
> +			     DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST);
> +	ratelimit_state_init(&dev->aer_report->uncor_log_ratelimit,
> +			     DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST);
>   
>   	/*
>   	 * We save/restore PCI_ERR_UNCOR_MASK, PCI_ERR_UNCOR_SEVER,
> @@ -697,6 +706,7 @@ void aer_print_error(struct pci_dev *dev, struct aer_err_info *info,
>   {
>   	int layer, agent;
>   	int id = pci_dev_id(dev);
> +	struct ratelimit_state *ratelimit;
>   
>   	if (!info->status) {
>   		pci_err(dev, "PCIe Bus Error: severity=%s, type=Inaccessible, (Unregistered Agent ID)\n",
> @@ -704,6 +714,14 @@ void aer_print_error(struct pci_dev *dev, struct aer_err_info *info,
>   		goto out;
>   	}
>   
> +	if (info->severity == AER_CORRECTABLE)
> +		ratelimit = &dev->aer_report->cor_log_ratelimit;
> +	else
> +		ratelimit = &dev->aer_report->uncor_log_ratelimit;
> +
> +	if (!__ratelimit(ratelimit))
> +		return;
> +
>   	layer = AER_GET_LAYER_ERROR(info->severity, info->status);
>   	agent = AER_GET_AGENT(info->severity, info->status);
>   
> @@ -749,12 +767,15 @@ void pci_print_aer(struct pci_dev *dev, int aer_severity,
>   	u32 status, mask;
>   	const char *level;
>   	struct aer_err_info info;
> +	struct ratelimit_state *ratelimit;
>   
>   	if (aer_severity == AER_CORRECTABLE) {
> +		ratelimit = &dev->aer_report->cor_log_ratelimit;
>   		status = aer->cor_status;
>   		mask = aer->cor_mask;
>   		level = KERN_WARNING;
>   	} else {
> +		ratelimit = &dev->aer_report->uncor_log_ratelimit;
>   		status = aer->uncor_status;
>   		mask = aer->uncor_mask;
>   		tlp_header_valid = status & AER_LOG_TLP_MASKS;
> @@ -772,6 +793,9 @@ void pci_print_aer(struct pci_dev *dev, int aer_severity,
>   
>   	pci_dev_aer_stats_incr(dev, &info);
>   
> +	if (!__ratelimit(ratelimit))
> +		return;
> +
>   	aer_printk(level, dev, "aer_status: 0x%08x, aer_mask: 0x%08x\n", status, mask);
>   	__aer_print_error(dev, &info, level);
>   	aer_printk(level, dev, "aer_layer=%s, aer_agent=%s\n",